Cancer being a complex disease is well implicated to deregulated activity of numerous cellular proteins ultimately accounting for functions of cell division and survival etc.Molecular oncological evidences point microtubules and their associated proteins called MAPs as one of the most vital proteins to elicit tumour malignancy at the cellular level.In this dissertation, a MAP protein called HPIP has been investigated for its role in polymerization of cytoskeleton, microtubules and cancer disease progression.Preliminary lines of experiment conducted under in vitro conditions enabled us to interpret HPIP as a factor promoting the polymerization of microtubules, the head apparatus for chromosomal congression and segregation during real time cell division.
Table of Contents
1) Aim of the study
2) Introduction
3) Materials and Methods
4) Results
5) Discussion
6) References
Research Objectives and Focus Areas
The primary objective of this research is to characterize the functional role of the Hematopoietic PBX Interacting Protein (HPIP) in regulating microtubule dynamics under in vitro conditions, given its known role as a scaffold protein in estrogen receptor (ERα) signaling and cell survival pathways.
- Functional characterization of HPIP protein interaction with microtubule networks.
- Evaluation of HPIP's role as a potential nucleotide-sensitive protein via GTP binding.
- Assessment of HPIP protein's potential protease activity in liver homogenates.
- Optimization of recombinant GST-HPIP expression and purification for biochemical assays.
Excerpt from the Book
Haematopoietic PBX1 interacting Protein (HPIP/PBXIP1)
HPIP is a novel protein which acts as a repressor of the transcription factors. By yeast two hybrid screening it was discovered that the homeodomain containinig PBX family proteins including PBX-I, II, III were binding to this strange protein HPIP (C.Abramovich et al., 2000). The level of expression of HPIP synchronously coincides with that of the PBX proteins in the CD 34+ haematopoietic progenitor cells and regulate their activity.The mechanism that is proposed for HPIP mediated repression of PBX function is the binding of HPIP to E2A-PBX at a non-homeodomain site that subsequently inhibits the formation of transcriptionally active PBX-HOX protein complex and hence the HOX protein mediated transcription. HPIP protein contains 731 amino acids with a molecular weight of 80kD. This is the first non-homeodomain binding protein to be discovered with no significant homology to the other known proteins so far reported.
HPIP is often localized in cytosol but traces also found in the nucleus and it is found to interact extensively with cytoskeleton fibres especially microtubules (C.Abramovich et al., 2000 & Manavathi et al., 2006). The transcriptional repression activity of HPIP is primarily attributed to the presence of a nuclear export signals (NES) and two functional nuclear localization signals (NLSs). However it is found that an effective binding of HPIP requires the presence of a complete homeodomain in PBX protein. It is still unclear about the extracellular signals that trigger the nucleus and cytoplasmic shuttle of HPIP and the post translational modifications that are necessarily to be made on HPIP for it’s sequestration from microtubules.
Summary of Chapters
1) Aim of the study: Outlines the research context regarding ERα signaling, the role of microtubules, and the investigation of HPIP's specific function in microtubule dynamics.
2) Introduction: Provides a comprehensive background on estrogen hormone action, ERα signaling pathways, the biological importance of microtubules, and the current knowledge on HPIP.
3) Materials and Methods: Details the protocols for plasmid isolation, E. coli transformation, protein overexpression and purification, and the specific assays used to test HPIP functionality.
4) Results: Presents the experimental data regarding the successful cloning, overexpression, and purification of GST-HPIP, alongside findings from interaction studies.
5) Discussion: Interprets the experimental findings, placing them in the context of HPIP's role as a microtubule-associated protein and its potential regulatory function.
6) References: Lists the scholarly sources and literature utilized to support the experimental approach and analysis.
Keywords
HPIP, Microtubule dynamics, Estrogen receptor, ERα, Scaffold protein, GTP binding, Breast cancer, Signal transduction, Protein purification, GST-tag, Cell survival, Tubulin polymerization, Transcription factor, Cytoskeletal fibers, Molecular oncology.
Frequently Asked Questions
What is the core subject of this research?
The research investigates the functional role of the HPIP protein, specifically its influence on microtubule dynamics and its interaction with cellular signaling components.
What are the primary thematic areas covered?
The study centers on molecular biology, focusing on hormone signaling (ERα), cytoskeletal protein regulation (microtubules), and protein-protein interaction analysis in a cancer research context.
What is the main objective of the thesis?
The aim is to determine how HPIP, previously identified as an ERα scaffold, impacts microtubule assembly and stability, and whether it exhibits nucleotide-binding or protease-like activities.
Which methodology is applied in the study?
The study employs molecular cloning, IPTG-inducible recombinant protein expression, affinity chromatography purification, Western blotting, spectrofluorimetry, and turbidimetric assays for monitoring microtubule polymerization.
What topics are discussed in the main body?
The body covers the signaling mechanisms of estrogen, the structure and regulation of microtubules, the molecular characterization of HPIP, and the step-by-step documentation of the experimental workflows.
How is HPIP characterized in this work?
HPIP is characterized as a novel, microtubule-associated protein that acts as a scaffold, with findings indicating it is sensitive to GTP and involved in complex signaling pathways.
Does HPIP exhibit protease activity according to this study?
Experimental assays involving liver homogenates revealed an absence of proteolytic activity, suggesting HPIP is not associated with protease functions under the conditions tested.
What does the spectrofluorimetric analysis of HPIP and GTP reveal?
The analysis shows a shift in emission intensity upon incubation of HPIP with GTP, confirming the formation of an HPIP-GTP complex, which implies nucleotide sensitivity.
How does HPIP influence microtubule polymerization kinetics?
The study indicates that HPIP incubation increases the velocity of the polymerization reaction, although the polymerization does not proceed to full completion, suggesting a complex regulatory role.
- Quote paper
- Rajasekar Gunasekaran (Author), 2009, Role of HPIP, a cytoplasmic regulator of ER-Alpha in microtubule dynamics, Munich, GRIN Verlag, https://www.hausarbeiten.de/document/183307
